Volume polarization gratings inscribed in glass with femtosecond lasers

The discovery of the formation of nanogratings when irradiating fused silica glass with ultrashort laser pulses in 2003 may have opened a new generation of compact and long life time optical devices. 3D-writing, thermal stability up to 1000 °C and virtually unlimited lifetime at room temperature make optics based on nanogratings of great potential for compact sensors or devices that work in adverse environmental conditions [1]. In addition, nanogratings behave as subwavelength structures in the visible and NIR spectrum, so that they allow micro-sized waveplates with controllable retardance and fast-axis orientation and, thus, they are expected to allow the fabrication of almost any design of polarization device in glass [2]. In this work we study volume polarization gratings (VPOG) in glass with special focus on the self-imaging of the grating produced by the Talbot effect. The experimental results are compared with the theoretical planar polarization gratings described by Scalar Diffraction Theory.